CMOS analog integrated circuits (such as operational amplifiers), and the use of class AB amplifiers as output stages thereof, are well known in the analog IC art. Heretofore, however, such amplifiers suffered by reason of their complexity (typically of the associated bias circuitry) and their requirements for relatively high operating voltages.
In accordance with the present invention, a CMOS operational amplifier is provided with improved input, predriver and output stages that overcome drawbacks of the prior art. The input stage features high gain and a very small offset voltage. The predriver and output stages cooperate to yield low distortion class AB operation with a minimum of circuit complexity. The resulting amplifier can be operated with a single 3 volt power supply and is ideal for driving large capacitive loads in systems requiring very low power consumption.
The foregoing and additional features and advantages of the present invention will be more readily apparent from the following detailed description thereof, which proceeds with reference to the accompanying drawings.